Hypoxia evokes a regulated decrease in deep body temperature (Tb).
Hydrogen sulfide (H2S), a signaling molecule that belongs to the
gasotransmitter family, has been demonstrated to participate in several brain-mediated responses. Rostral ventrolateral medulla (RVLM) is a brainstem region involved in thermoregulation. Recently, it has been shown that exogenous H2S modulates RVLM activity. In the present study, we investigated whether endogenously produced H2S in the RVLM plays a role in the control of
hypoxia-
induced hypothermia. Tb was measured before and after bilateral microinjection of
aminooxyacetate (AOA, 0.2, 1 and 2 pmol/100 nl, a
cystathionine β-synthase, CBS, inhibitor) or vehicle into the RVLM followed by a 60-min normoxia (21% inspired O2) or
hypoxia (7% inspired O2) exposure. Microinjection of AOA or vehicle did not change Tb during normoxia. Exposure to
hypoxia evoked a typical decrease in Tb. Microinjection of AOA (2 pmol) into the RVLM followed by
hypoxia significantly attenuated the decrease in Tb. Thus, endogenous H2S in the RVLM seems to play no role in the maintenance of basal Tb, whereas during
hypoxia this gas plays a cryogenic role. Moreover, RVLM homogenates of rats exposed to
hypoxia exhibited a decreased rate of H2S production. Our data are consistent with the notion that during
hypoxia H2S synthesis is diminished in the RVLM facilitating
hypothermia.